1. Field of the Invention
This invention relates to a method for simultaneously cleaning and disinfecting contact lenses and compositions for the same. More specifically, the present invention is directed to a non-oxidative method for simultaneously cleaning and disinfecting contact lenses by soaking the lenses in an aqueous solution containing a disinfecting agent to which is added a proteolytic enzyme.
2. Description of Related Art
The growth of the contact lense industry has led to a dramatic increase in the number of lenses and care regimens in the marketplace. Designing care regimens to meet the needs of all possible permutations has become a challenge to the industry. In particular, a goal of the lens care industry is to simplify the lens care regimen to obtain greater patient compliance.
In the normal course of wearing contact lenses, tear film and debris consisting of proteinaceous, oily, sebaceous, and related organic matter have a tendency to deposit and build up on lense surfaces. As part of the routine care regimen, contact lenses must be cleaned to remove these tear film deposits and debris. If these deposits are not properly removed, both the wetability and optical clarity of the lenses is substantially reduced causing discomfort for the wearer.
The only safe and effective means found to date for removing protein build-up is the use of enzymes, whose hydrolytic activity reduces the proteinaceous materials to small, water soluble subunits. Particularly useful are proteolytic enzymes or proteases. U.S. Pat. No. 3,910,296 discloses the use of proteases for cleaning contact lenses.
Further, contact lenses, especially those made from hydrophilic materials, must be continuously disinfected to kill any harmful microorganisms that may be present or grow on the lenses. Microorganisms that are incorporated in the panel of microorganisms required by the 1985 U.S. FDA guidelines for contact lens solutions for disinfection efficacy include Serratia marcescens ("S.M.") (ATCC 14041), Staphylococcus epidermidis ("S.E.") (ATCC 17917), Pseudomonas aeruginosa ("P.A.") (ATCC 15442) and Candida albicans ("C.A.") (ATCC 10231).
A number of methods for disinfecting contact lenses have been used such as the use of high temperatures, the use of oxidative chemicals, and the use of antimicrobial agents. U.S. Pat. Nos. 4,407,791 and 4,525,346 show the polyquaternary ammonium contact lens disinfecting agent 1-tris (2-hydroxyethyl) ammonium-2-butenyl-4-poly [1-dimethyl ammonium-2-butenyl]-w-tris (2-hydroxyethyl) ammonium chloride salt. European patent application 89810477.3 shows the disinfecting agent dodecyl-dimethyl-(2-phenoxyethyl)-ammonium bromide. U.S. Pat. No. 4,029,817 assigned to Allergan, Inc. shows the contact lens disinfecting agent tallow triethanol ammonium chloride. U.S. Pat. No. 4,758,595 shows the hexamethylene biquanide contact lens disinfecting agent.
In addition to cleaning and disinfecting, contact lenses must also be rinsed. A typical solution for rinsing is a normal saline solution. If the lenses are inserted in the eye without first rinsing, the eyes will burn and can become seriously irritated.
New methods have been developed which can remove proteinaceous material from contact lenses while disinfecting the lenses. For example, U.S. Pat. No. 4,614,549 discloses a single-step method of cleaning and disinfecting contact lenses in aqueous solutions of proteolytic enzymes at temperatures of between 60.degree. C. and 100.degree. C. This method requires the use of electrical disinfecting apparatus and elevated temperatures. U.S. Pat. No. Re. 32,672 assigned to Allergan, Inc. discloses a method by which the lenses are immersed in a solution containing peroxide and a peroxide-active enzyme. Japanese patent application Showa 49-45012 discusses cleaning and sterilizing contact lenses by contacting the lens with an aqueous solution containing a protease and sterilizing agent such as triethanol tallow ammonium chloride, thimerosal and a wide range of reducing agents. U.S. Pat. No. 5,096,607 discloses a method for simultaneously cleaning and disinfecting contact lenses by contacting the lenses with a solution containing a proteolytic enzyme and either a polymeric quaternary ammonium salt or a biguanide and adjusting the osmotic value of the solution to a level which does not inhibit the activity of the quaternary ammonium salt or the biguanide. This patent describes a wide range of useful proteolytic enzymes (in kind and amount) and a wide range of quaternary ammonium salts and biguanides (in kind and amount). All of the simultaneous cleaning and disinfecting methodologies typically require the step of rinsing the cleaned and disinfected lenses.